Public buses in major cities around the country are being equipped with microphone-enabled surveillance systems capable of picking up passenger conversations.

Audio-enabled surveillance systems are being installed on public buses in major cities across the country, Wired reported. The systems contain video cameras and microphones whose recordings can either be accessed remotely via web server in real time or stored for later collection. Officials have either installed or are procuring such systems in San Francisco, Calif., Eugene, Ore., Traverse City, Mich., Columbus, Ohio, Baltimore, Md., Hartford, Conn., and Athens, Ga.

The installation of these systems has raised both privacy and security concerns. Not only can private conversations be picked up by the systems, but if they are not properly secured, hackers can use the systems to track the position of buses.

Transit officials in San Francisco are proceeding with a $5.9 million contract to add audio surveillance systems to 357 buses and trolley cars. Funded entirely by a grant from the Department of Homeland Security, the contract can be expanded to 600 more vehicles, according to Wired.

Baltimore, Md., intended to install audio surveillance systems on public buses in 2009, but abandoned the effort due to protests from civil liberties groups who claimed that such systems violated constitutional protections and wiretapping laws. Following assurances from the state attorney general that signage announcing the surveillance system would help address these complaints, the city is now moving forward with audio surveillance system installation on 350 public buses.